Thermoguard Thermoproof Exterior Fluid
  • Thermoguard Thermoproof Exterior Fluid

Thermoguard Thermoproof Exterior Fluid


Thermoguard Thermoproof Exterior Fluid is a penetrating fire proof fluid for bare wood such as sleepers, fencing, cladding and decking. The weather resistant, water-based, non flammable formula enables safe application by untrained and inexperienced users.

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Thermoguard Thermoproof Exterior Fluid

Thermoguard Thermoproof Exterior Fluid is a penetrating fire proof fluid for wood.

Intended Use

Fire protection for bare timber sleepers, fencing, cladding and decking.


Durable clear fire and flame resistant fluid for external and internal wood. Weather resistant. Water-based, non flammable formula enables safe application by untrained and inexperienced users.

How it Works

Penetrates deep into porous wood. When exposed to fire Thermoguard Thermoproof Exterior Fluid creates an inert layer within the wood’s surface which insulates the wood from fire, preventing flamespread.

UKAS Fire Test Standards

  • BS EN Class B s2 dO
  • Class O

For 30 or 60 mins contact Technical Dept.


  • Apply at 3.5m² per litre. Normally applied in 3 coats @ 10.5m² per litre but can be applied in 2 coats at 7m² per litre on very porous rough sawn wood.
  • Ensure each application has fully soaked in before applying the next. Allow a minimum of 2 hours between applications.
  • Apply to small test patch prior to main application.


19m² per 5L

Application Method

Brush, Roller, Spray.

Application Conditions

  • Apply to dry wood (below 18% moisture) above 5°C in dry conditions prior to painting or waterproofing. Where possible wait until the wood has thoroughly dried out before fixing.
  • Allow adequate time for the wood to dry out after treatment before applying any coating.*

*Contact the Technical Department.

Limitations (Stained, Varnished or Painted Wood)

  • For treatment with Thermoguard Thermoproof Exterior Fluid to be effective it needs to be able to penetrate the wood.
  • Remove any water resistant coating, sealer coat, waxy feel, glossy sheen, or waterproofing effect created by a previous treatment or preparation before application.

Project Fire Certification

Thermoguard issue a Certificate of Supply on request for projects for insurance, Fire and Building Control Authority and Client Records.

New Fire Regulations & Tests Explained

  • The new fire standard BS EN test lasts 20 mins. with airflow replaces the old BS 476 tests which lasted 10 mins and strangely restricted airflow.
  • The new standard for flamespread and heat release Class B replaces Class O.

The new BS EN tests also monitor -

  • Smoke & Gas “s” – s1 + s2 are none or very low & compliant, s3 = moderate smoke, s4 = heavy smoke.
  • Flaming Droplets or Airborne particulates – dO is none, d1 = low, d2 = moderate, d3 = high levels.

IMPORTANT FIRE PRODUCTS NOTICE: The information displayed on this website should be used as a guide ONLY and our Technical Department should be contacted to obtain a tailored specification and any advice necessary before you place an order for fire protection products. Fire protection products are non-returnable except in accordance with Condition 8 of the Terms and ConditionsWe will not be held liable for any resulting damage to property, human life or monetary costs incurred due to the incorrect specification you have prepared or use of fire protection products caused by your negligence, including your failure to have contacted us to obtain the relevant advice/specification.

It is your responsibility to read the Product Data Sheets (available below) before you place an order and prior to application of the product. The content of this website is our best recommendation and is not advice. Coverage rates quoted are approximate, you agree that coverage depends on the condition of the substrate, surface absorption, texture and application method. We ALWAYS recommend a trial area is coated to ensure the product meets your requirements before use.

Product Details

Data sheet

Brush, Roller, Spray
10.5m² per litre
Touch Dry
2 Hours

Customer agrees that before placing an Order, Customer has read and understood the most up to date Product Data Sheet for the Product. Where we have access to the Product Data Sheet from the manufacturer, we will either provide a copy on request, or include a link to the Product Data Sheet available on the manufacturer’s website. Customer further agrees that we have no liability for any errors or omissions contained within the Product Data Sheets. For more information, please see our Terms & Conditions of Sale.

questions Nick pilkington on 2019-05-30 06:35:54

I need to cover a garage to satisfy building control. Approx 70 square metres, feather edge from 1 inch down to a quarter, larch, bare wood, rough sawn. I need a colourless finish. What would be suitable?


Could you advise the Level of Fire Protection required please, i.e. Class 1, Class 0, 30min, 60min, etc?

questions Mark Ransom on 2019-05-15 18:20:53

I am looking for a paint product to give 60 minute fire protection on a pine softwood garage to satisfy a Building Inspector. I would also want a regulation certificate.


Thermoguard Thermoproof Exterior Fluid is not suitable to provide 60min fire protection, to enable us to advise the correct product/system to use, please provide us with as much of the following information as possible;

  • Size of surface area to paint
  • Timber thickness
  • Type of Timber surface (i.e. T&G, feather edge / shiplap cladding, solid panels / sheets, etc.)
  • Internal or external
  • Use (i.e. floor, wall cladding, ceiling, etc.)
  • Clear or coloured coating required?
  • Bare or previously coated?
questions Adam Lay on 2018-12-11 12:38:35

Hello! I am looking at fireproof coatings and in order to satisfy my building inspector, I need a certificate to show one of your coatings/impregnators have a certificate for having been tested on oak. These are the two products I'm looking at: Can you please confirm if there is a test certificate on oak available for either of these products please? The Zeroflame text specifically mentions it has been tested on oak as well as other timbers. Is it possible to get hold of a copy of that certificate please? Many thanks in advance. Adam Lay


Copies of the testing on oak have now been emailed to you.

questions me on 2018-12-04 08:01:01

Is this product compatible with Sadoline extra wood stain and berrettine used as an overcoat ?(,sgro:iv,cs:1&sa=X&ved=2ahUKEwj2-MCr2IXfAhVKBMAKHTnDAHwQ-K4BegUIDxCkAQ) or berrettine ( .


No, if a woodstain finish is required then Thermoguard recommend the use of Sikkens Cetol WF 771 over their Thermoproof Exterior Fluid. Wait until Thermoproof Exterior has fully dried before application.


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